Abstract

After pretreatment of an Escherichia coli C culture with mitomycin C, the deoxyribonucleic acid (DNA) synthesis of the bacteria, as well as that of infecting phage φX174, is very largely inhibited. Although the bacterial DNA synthesis
is similarly inhibited by mitomycin C in uvr^(-)mutants
(P. Howard-Flanders, R. P. Boyce, and L. Theriot, Genetics 53:1119, 1966), phage DNA synthesis and progeny formation take place in a normal manner (B. H. Lindqvist and R. L.
Sinsheimer, J. Mol. Biol. 30:69, 1967). The reason for this behavior of the uvr^- cells is not understood. Since it is known that uvr^+ cells do not reactivate double-stranded ultraviolet-damaged phage DNA in the presence of adequate
concentrations of caffeine (W. Sauerbier, Biochem. Biophys. Res. Commun. 14:340, 1964), it was of interest to test the ability of mitomycin C-treated uvr^+ cells to produce phage under these conditions.